1. Field of the Invention
The present invention relates to a recording apparatus for recording an image in accordance with input data.
2. Related Background Art
In a prior art recording apparatus (hereinafter referred to as a printer), a power switch serves as a switch for a power supply circuit, and when the printer power supply is turned on, a power is supplied to a control circuit of a printer, and when the printer power supply is turned off, no power is supplied. However, this method includes the following drawbacks:
(1) When the power supply is turned on, it is necessary for a carriage to detect an absolute position (home position detection). PA1 (2) Since it is not possible to prevent a recording head from adhering when the power supply is turned off, a recovery control of the recording head is required when the power supply is turned on. PA1 (3) Since the recovery control of the head is required each time the power supply is turned on, an amount of ink used increases because of the repetitive turn-on/off of the power supply. PA1 (4) If a power-off sequence such as paper ejection and capping of a head is to be carried out when the power supply is turned on, a special circuit to control the apparatus such that the supply of the power is not stopped until the termination of the power-off sequence is required.
In order to solve the above problems, it has been proposed to not use the turn-on/off of the printer by the power switch to turn on and off the power supply circuit but use it to set a print enable state and a print disable state.
However, when the turn-on/off of the printer power supply is used to set the print enable state and the print disable state instead of using it for turning on and off the power supply circuit, there is a possibility that a host computer may send print data in accordance with an interface signal of the printer because the interface signal is valid even during the off-state of the printer power supply.
Thus, in the prior art printer in which the on/off-state of the printer power supply corresponds to the on/off-state of the power supply circuit, the interface signal to the printer is at a low level or in a high impedance state when the printer power supply is turned off. Among others, a signal line which indicates that the printer does not accept data such as a busy signal (data is not acceptable when it is active) which indicates whether the printer can accept the data or not and which is sent from the printer to the host, an error signal which indicates an off-line state or any trouble or a PE signal which indicates that papers have been exhausted, is at the high impedance state, and the signal line is at the high level if it is pulled up by the host, and at the low level if it is pulled down.
Thus, when the printer power supply is turned off, the host pulls up or down the signal line to render the busy signal, the error signal or the PE signal active in order to prevent the data from being sent to the printer.
However, when the on/off-state of the printer power supply is used to control the print enable state and the print disable state instead of using it to turn on/off the power supply circuit, the busy signal, the error signal and the PE signal are not in the high impedance state even when the printing operation is not carried out because the power is supplied to the control circuit of the printer, and hence there is a possibility that the print data may be sent from the host.